An electronic energy sample analysis device

ABSTRACT

An apparatus for analysis of a sample by bombardment under high vacuum (10 5 mm.Hg.), wherein the sample is received in a rotatable turret having two through bores which sealingly mate alternately with two apertures. One of these apertures communicates directly with an enclosure under high vacuum and the sample is bombarded therethrough, and the other aperture leads to a conduit adapted to be alternately vented to atmosphere and then reduced to an intermediate vacuum level (e.g., 10 3 mm.Hg.). The aperture is vented to enable a sample holder to be removed and clamped and the intermediate level is then reached. The turret is then rotated to interchange the position of the through bores. During the rotation the through bore with the fresh sample is briefly opened into a further aperture leading by a conduit into the evacuated enclosure at a point remote from the bombardment zone so that the through bore is evacuated without significantly affecting the vacuum near the bombardment zone.

United States Patent 3,356,844 12/1967 Houbart AN ELECTRONIC ENERGYSAMPLE ANALYSIS DEVICE 4 Claims, 3 Drawing Figs.

U.S. Cl 250/495 Int. Cl 1-101j 37/26 Field of Search 250/49.5

References Cited UNITED STATES PATENTS Primary ExaminerArchie R.Borchelt Altorney Frank R. Trifari ABSTRACT: An apparatus for analysisof a sample by bombardment under high vacuum (10 mm.l-Ig.), wherein thesample is received in a rotatable turret having two through bores whichsealingly mate alternately with two apertures. One of these aperturescommunicates directly with an enclosure under high vacuum and the sampleis bombarded therethrough, and the other aperture leads to a conduitadapted to be alternately vented to atmosphere and then reduced to anintermediate vacuum level (e.g., l0 mm.Hg.)t The aperture is vented toenable a sample holder to be removed and clamped and the intermediatelevel is then reached. The turret is then rotated to interchange theposition of the through bores. During the rotation the through bore withthe fresh sample is briefly opened into a further aperture leading by aconduit into the evacuated enclosure at a point remote from thebombardment zone so that the through bore is evacuated withoutsignificantly affecting the vacuum near the bombardment zone.

PATENTEBNUY 2 mm FIG 2 FIGQII.

AN ELECTRONIC ENERGY SAMPLE ANALYSIS DEVICE The present inventionrelates to improvements in devices used for sample analysis in processesin which the samples are placed under vacuum before being subjected toanalysis, and particularly when analysis is to-be effected byfluorescence and/or direct X-ray emission techniques, the said samplesbeing placed, at least at the actual moment at which analysis iseffected, in an enclosure in which there is a particularly high vacuum,i.e., ofthe order of mm. Hg.

An earlier US. Pat. No. 3,356,844 describes a device for the analysis ofsamples of the type above described and comprising:

a. an enclosure and a device for placing the enclosure under a vacuumofthe order to 10 mm. Hg,

b. an electron emission device for emitting electrons into the enclosureand ensuring that their energy is sufficient to cause the appearance ofa secondary X-ray on a sample struck by the electrons,

c. an aperture provided in the enclosure,

d. a rotary support on which are mounted one or more assemblies, eachcomposed of a cover, a sample and a sample support, each cover beingsecured in a sealed manner to the support which is able to slide, alsoin a sealed manner, on the outer wall of the enclosure, owing to theprovision of a suitable packing which is preferably integral with thesupport, the latter being able to assume positions relative to theaperture such that each sample support may be located in turn in asealed manner opposite the aperture and the sample is subjected in thisposition to electronic bombardment,

e. a device for producing a high vacuum in at least one of the areaslocated between a cover and the wall of the enclosure.

In practice the assemblies were three in number and were located inrecesses in the rotary support at an angle of 120 relative to oneanother about the axis of rotation of the support. Each sample is movedinto three successive positions:

1. A sample change position in which the pertinent recess was at thatmoment connected to a vane-type pump having a device for producingatmospheric pressure and able to produce, in the area between the wallof the enclosure and the cover, a vacuum of 10" mm. Hg.

2. A waiting position in which the recess is connected to a diffusionpump which raises the vacuum of 10" mm. Hg to 10" mm. Hg, which is thesame as that existing within the enclosure.

3. A working position in which the recess is located in front of theaperture provided in the enclosure and analysis may be carried out,radiation reaching the sample through the aperture.

This device operates satisfactorily, particularly because of the designof the seal which is an important feature thereof.

The present invention relates to improvements in the device describedabove which make it possible on the one hand to simplify the apparatusby reducing the number of diffusion pumps to one while on the other handsubstantially reducing the minimum time required to obtain the resultsof a sample analysis.

The invention accordingly consist in a device for sample analysis,wherein the device comprises:

a. an enclosure and a device for producing a vacuum of the order of 10mm. Hg. within the enclosure,

b. a device for emitting X-rays and both X-rays and/or electrons areherein defined as electronic energy into the enclosure and ensuring thatthe energy is sufficient to cause the appearance of secondary X-rays tobe emitted from a sample struck by the electronic energy,

c. a first aperture provided in the enclosure to allow passage of theX-rays and electrons directed on to the sample,

d. a second aperture provided in the enclosure and connected, at theinside of the enclosure, to one end of a conduit, the other end of whichis open and is located in the enclosure at a point sufficiently distantfrom the X-ray and electron emitter and sufficiently near thevacuum-producing device for any fluctuation in vacuum occurring at theother end to be practically eliminated by the vacuum-producing devicebefore it can spread to the vicinity of the X-ray and electron emitter,

e. a support on which are mounted two assemblies, each composed of acover and a sample support, each assembly being integral with thesupport, while the cover is secured in a sealed manner to the support,the sample holder and any sample thereon being then located at theenclosure side of a hole which extends right through the support whichis able to slide in a sealed manner on the outer wall of the enclosure,the support being able to assume fixed positions relatively to the twoapertures provided in the wall such that each hole is located in frontof the second and then in front of the first aperture, the support andits seal being large enough to close the two apertures in a sealedmanner when no hole is located in front of the apertures,

f. a third aperture provided in the wall. of the enclosure or in theextension thereof, to which, on the enclosure side, there is connectedin a sealed manner a passage connected to a vacuum-producing device ableto produce at least a 10" mm. Hg. vacuum, and to a device for producingatmospheric pressure, the support also being able to slide in a sealedmanner on the wall or extension thereof, so that each hole may bebrought opposite the third aperture.

Preferably, thewall on which the support slides is flat, the supportrotates and the two holes are located diametrically opposite each otherin the support and equidistant from the axis of rotation, the first andthird apertures being located so that each of the two holes may belocated successively opposite the first one and then the other aperturewhen the support moves l about its axis of rotation, while the secondaperture is arranged so as to be opposite either of the holes for abrief period during the time when the hole moves from its positionopposite the third aperture to that opposite the first aperture.

The invention will now be described with reference to the accompanyingdrawings which illustrate the invention but in no restrictive manner.

ln the drawings:

FIG. 1 is a diagrammatic sectional view of the device; and

F108, 2 and 3 show details of the device of HO. 1.

The device illustrated comprises an enclosure 1 in which a vacuum of 10Torr (mm. Hg) is maintained by means of a high output diffusion pump 2.This enclosure is closed near the top by a wall 3 which forms the baseof a circular tray having three apertures 4, 5 and 6, the first two, 4and 5, of which are located diametrically opposite one another while thethird, 6 which is smaller, is located at to the first two relatively tothe center of the wall 3 (see FIG. 3). A turret 7, which is circular inshape, is held in a sealed manner against the outer face of the wall 3and is coaxial with the axis 8 of the wall 3 and provided with two bores9, 10 located diametrically opposite each other and at the same distancefrom the axis 8 as are the apertures 4, 5 and 6 so that rotation of theturret 7 causes the recesses 9 and 10 to pass in front of the apertures4, 6, 5 in succession. The seal between the turret and the wall isachieved by means of a special seal comprising two O-rings 11 and 12coaxial with the axis 8 and connected together by six spokes positionedat an angle of 60 relative to one another and also constituting part ofthe seal which is solid with the turret 7. Each of the bores 9 and 10 isclosed at the outside by a sealed cover 13, 14 respectively, each coverbeing provided with a sample holder 36 and a sample 37 located in thecorresponding bore.

In addition, the aperture 4 is connected in a sealed manner to a conduit15 leading to a vane pump 16 through a valve 17. The aperture 5 islocated exactly opposite an X-ray tube 18, the outlet window of whichhas been removed, the tube 18 being mounted in the sidewall 19 of theenclosure 1, while the aperture 6 is connected at the enclosure side toa tube 20, the lower end 21 of which is substantially lower than theX-ray tube 18.

The diffusion pump 2 is provided with a screen 22 which may be adjustedfrom outside the enclosure by means of a lever 23. The screen 22 restsin a sealed manner on a circular support 24 solid with the body of thepump. A line 25 containing a valve 26 connects the vane pump 16 eitherto the enclosure or to the diffusion pump through a reservoir 27, Itshould also be pointed out that an air intake device 28 is located inthe conduit 15 while a cooling jacket 29 (using freon) is connected tothe diffusion pump. An X-ray measuring device 30 mounted in the wall 19essentially comprises, located within an auxiliary enclosure 31 in whichthe pressure is 5X 1 Torr, a collimator 33, a crystal 34 and a counter35 suitably arranged. The collimator 33 obturates completely and in analmost sealed manner the wall 32 common to the enclosure 1 and theenclosure 31. The pressure of l0 Torr reigning in the enclosure 31 isobtained by means of the diffusion pump 2 which acts through thecollimator 33, the difference in pressure being due to the loss incharge through the collimator.

The complete device thus described operates as follows:

At the beginning of the operation, there is no vacuum in eitherenclosure. The device 28 is closed, the valve 17 connects the conduit 15and the pump E6, while the valve 26 connects the tank 27 and the insideof the diffusion pump 2 to the same pump. The vane pump 16 is operateduntil the vacuum obtained is ofthe order of IO Torr. At that moment thevalve 26 is shifted so as to close the inlet to the tank 27 and the vanepump, which is connected to the enclosure 1, sets up a vacuum of Torrtherein. The pump is then reconnected to the tank 27, the screen 22 ismoved upwards by means of the lever 23, which is made possible by thebalance of pressure on either side of the screen, and the diffusion pump2 is operated so as to produce a vacuum of 10" Torr in the enclosures 1,including the X-ray tube, and a vacuum of 5X10" Torr in the enclosure31. The X-ray tube is then switched on as is the measuring device.

The turret 7 is loaded with a single sample 37 which is located in thebore 9 opening into the aperture 4 and supported by the cover 13. Oncethe vacuum in each of the enclosures has reached the value desired, theturret 7 carrying the sample to be analyzed is rotated through 180. Atthe moment at which the sample-which is then under a vacuum of 10Torrpasses in front of the aperture 6, the effect of the low pressure inthe enclosure 1 evacuates the small quantity of air which is in therecess instantaneously through the tube 20, essentially withoutdisturbing the level of vacuum in the enclosure 1. Moreover, the lowposition of the aperture 21 of the tube 20 prevents any fluctuation invacuum reaching the X- ray tube and disturbing its functioning. Thesample is then bombarded with electrons as it reaches its position infront of the aperture 5, without there being any fluctuations in thepressure within the enclosure. During this period, the valve 17 isclosed and the bore 10 brought to atmospheric pressure by means of thedevice 28, the pump 16 and the tank 27 being protected from theatmospheric pressure by closure of the valve 17. The bore 10 is loadedwith a sample 37, the valve 26 is closed temporarily and the recessagain connected to the pump 16 so that the cycle can recommence. Thetime necessary for the completion of a cycle of operations (e.g., twosuccessive loadings) does not exceed 2 min. sec. and is often less thanthis. Moreover, the device, which only needs one diffusion pump, makesit possible to insert an urgent" sample in a series of samples foranalysis with particular rapidity and to effect its analysis by thefluorescence process in a very short time, since in the worst possiblecase there cannot be more than one sample to be analyzed which isalready loaded on the turret 7, thus reducing to a minimum the waitingtime required before the urgent sample can be inserted in the device andanalyzed.

The intermediate seal which ensures the tight connection between thesupport and the enclosure may take a number of forms, but particularlyadvantageous use may be made of the seal described in US. Pat. No.3,356,844 which allows the vacuum of IO Torr to be maintained in theenclosure, even when the turret is in motion, and ensures that there isno connection between the two bores provided in the turret. The

form of this seal also enables it permanently to se arate from eachother the second and third apertures (locate at 90 from each other) dueto the presence of spokes located at 60 to each other, since there isalways at least one spoke located between the two apertures andinsulating them from each other.

I claim:

1. An electronic energy sample analysis device comprising:

a. an enclosure and a means for producing a vacuum in the order of l0mm. Hg. within said enclosure,

b. means for emitting electronic energy in the enclosure of such amagnitude as to cause the emission of secondary X-rays from a samplestruck by the electronic energy,

c. a first aperture provided in the enclosure to allow passage of theelectronic energy directed on to a sample,

d. a second aperture provided in the enclosure and connected, at theinside of the enclosure, to one end ofa conduit, the other end of whichconduit is open and is located in the enclosure at a point intermediatethe electronic energy means and the vacuum producing means so that anyfluctuation in vacuum which occurs at said other end is essentiallyeliminated by the vacuum producing means before the fluctuation canspread to the electronic energy means,

e. a turret mounted in sealing engagement with the enclosure over saidapertures and having two bores in it, each bore being capped by a coverand containing a sample support adapted to support a sample, the coverbeing secured in a sealed manner to the turret and the sample holderbeing located at the enclosure end of each bore which extends throughthe turret and which turret slides in a sealed manner on the enclosure,the turret further being able to assume fixed positions relatively tothe two apertures such that the bores may be selectively locatedadjacent and placed in communication with said first and secondapertures; and

f. a third aperture provided in the enclosure, a conduit having one endconnected in a sealed manner to the enclosure side of the aperture, theother end being selectively engageable with a second vacuum producingmeans able to produce at least a 10 mm. Hg. vacuum and to atmosphericpressure, the turret also being slidable in a sealed manner so that eachbore may also be selectively brought adjacent and placed incommunication with the third aperture.

2. A device as claimed in claim 1, wherein the portion of the enclosurecontaining the three apertures and on which the turret slides is flat;the turret is rotatable and the two bores are located diametricallyopposite each other in the turret and equidistant from the axis ofrotation; the first and third apertures being located so that each ofthe two bores may be located successively adjacent and in communicationwith said first aperture then said third aperture when the turretrotates l about its axis of rotation, while said second aperture isarranged so as to be adjacent either one of the bores for a brief periodduring the time when the bore moves from its position adjacent the thirdaperture to that adjacent the first aperture.

3. A device as claimed in claim 1, wherein said means for emittingelectronic energy is an X-ray tube and the physical juxtaposition ofsaid other end of the conduit intermediate said X-ray tube and saidvacuum-producing means permits said vacuum-producing means to correctany fluctuation in vacuum before it can effect the functioning of saidX-ray tube.

4. A device as claimed in claim 1, wherein the portion of the enclosurecontaining said three apertures is flat, the axes of said bores aresubstantially perpendicular to said flat portion, and sealing means areplaced between said flat portion and said turret so that said turret canbe rotated to selectively bring said bores over said apertures whilemaintaining the vacuum in said enclosure and bores when they communicatewith the apertures.

1. An electronic energy sample analysis device comprising: a. anenclosure and a means for producing a vacuum in the order of 10 5 mm.Hg. within said enclosure, b. means for emitting electronic energy inthe enclosure of such a magnitude as to cause the emission of secondaryX-rays from a sample struck by the electronic energy, c. a firstaperture provided in the enclosure to allow passage of the electronicenergy directed on to a sample, d. a second aperture provided in theenclosure and connected, at the inside of the enclosure, to one end of aconduit, the other end of which conduit is open and is located in theenclosure at a point intermediate the electronic energy means and thevacuum producing means so that any fluctuation in vacuum which occurs atsaid other end is essentially eliminated by the vacuum producing meansbefore the fluctuation can spread to the electronic energy means, e. aturret mounted in sealing engagement with the enclosure over saidapertures and having two bores in it, each bore being capped by a coverand containing a sample support adapted to support a sample, the coverbeing secured in a sealed manner to the turret And the sample holderbeing located at the enclosure end of each bore which extends throughthe turret and which turret slides in a sealed manner on the enclosure,the turret further being able to assume fixed positions relatively tothe two apertures such that the bores may be selectively locatedadjacent and placed in communication with said first and secondapertures; and f. a third aperture provided in the enclosure, a conduithaving one end connected in a sealed manner to the enclosure side of theaperture, the other end being selectively engageable with a secondvacuum producing means able to produce at least a 10 3 mm. Hg. vacuumand to atmospheric pressure, the turret also being slidable in a sealedmanner so that each bore may also be selectively brought adjacent andplaced in communication with the third aperture.
 2. A device as claimedin claim 1, wherein the portion of the enclosure containing the threeapertures and on which the turret slides is flat; the turret isrotatable and the two bores are located diametrically opposite eachother in the turret and equidistant from the axis of rotation; the firstand third apertures being located so that each of the two bores may belocated successively adjacent and in communication with said firstaperture then said third aperture when the turret rotates 180* about itsaxis of rotation, while said second aperture is arranged so as to beadjacent either one of the bores for a brief period during the time whenthe bore moves from its position adjacent the third aperture to thatadjacent the first aperture.
 3. A device as claimed in claim 1, whereinsaid means for emitting electronic energy is an X-ray tube and thephysical juxtaposition of said other end of the conduit intermediatesaid X-ray tube and said vacuum-producing means permits saidvacuum-producing means to correct any fluctuation in vacuum before itcan effect the functioning of said X-ray tube.
 4. A device as claimed inclaim 1, wherein the portion of the enclosure containing said threeapertures is flat, the axes of said bores are substantiallyperpendicular to said flat portion, and sealing means are placed betweensaid flat portion and said turret so that said turret can be rotated toselectively bring said bores over said apertures while maintaining thevacuum in said enclosure and bores when they communicate with theapertures.